2 FreeRTOS.org V5.4.0 - Copyright (C) 2003-2009 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License (version 2) as published
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8 by the Free Software Foundation and modified by the FreeRTOS exception.
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9 **NOTE** The exception to the GPL is included to allow you to distribute a
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10 combined work that includes FreeRTOS.org without being obliged to provide
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11 the source code for any proprietary components. Alternative commercial
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12 license and support terms are also available upon request. See the
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13 licensing section of http://www.FreeRTOS.org for full details.
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15 FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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20 You should have received a copy of the GNU General Public License along
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21 with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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22 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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25 ***************************************************************************
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27 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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29 * This is a concise, step by step, 'hands on' guide that describes both *
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30 * general multitasking concepts and FreeRTOS specifics. It presents and *
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31 * explains numerous examples that are written using the FreeRTOS API. *
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32 * Full source code for all the examples is provided in an accompanying *
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35 ***************************************************************************
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39 Please ensure to read the configuration and relevant port sections of the
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40 online documentation.
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42 http://www.FreeRTOS.org - Documentation, latest information, license and
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45 http://www.SafeRTOS.com - A version that is certified for use in safety
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48 http://www.OpenRTOS.com - Commercial support, development, porting,
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49 licensing and training services.
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55 + Made serial ISR handling more complete and robust.
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59 + Split serial.c into serial.c and serialISR.c. serial.c can be
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60 compiled using ARM or THUMB modes. serialISR.c must always be
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61 compiled in ARM mode.
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62 + Another small change to cSerialPutChar().
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66 + In cSerialPutChar() an extra check is made to ensure the post to
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67 the queue was successful if then attempting to retrieve the posted
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73 BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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75 This file contains all the serial port components that can be compiled to
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76 either ARM or THUMB mode. Components that must be compiled to ARM mode are
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77 contained in serialISR.c.
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80 /* Standard includes. */
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83 /* Scheduler includes. */
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84 #include "FreeRTOS.h"
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88 /* Demo application includes. */
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91 /*-----------------------------------------------------------*/
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93 /* Constants to setup and access the UART. */
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94 #define serDLAB ( ( unsigned portCHAR ) 0x80 )
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95 #define serENABLE_INTERRUPTS ( ( unsigned portCHAR ) 0x03 )
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96 #define serNO_PARITY ( ( unsigned portCHAR ) 0x00 )
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97 #define ser1_STOP_BIT ( ( unsigned portCHAR ) 0x00 )
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98 #define ser8_BIT_CHARS ( ( unsigned portCHAR ) 0x03 )
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99 #define serFIFO_ON ( ( unsigned portCHAR ) 0x01 )
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100 #define serCLEAR_FIFO ( ( unsigned portCHAR ) 0x06 )
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101 #define serWANTED_CLOCK_SCALING ( ( unsigned portLONG ) 16 )
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103 /* Constants to setup and access the VIC. */
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104 #define serUART0_VIC_CHANNEL ( ( unsigned portLONG ) 0x0006 )
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105 #define serUART0_VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0040 )
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106 #define serUART0_VIC_ENABLE ( ( unsigned portLONG ) 0x0020 )
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107 #define serCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
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109 #define serINVALID_QUEUE ( ( xQueueHandle ) 0 )
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110 #define serHANDLE ( ( xComPortHandle ) 1 )
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111 #define serNO_BLOCK ( ( portTickType ) 0 )
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113 /*-----------------------------------------------------------*/
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115 /* Queues used to hold received characters, and characters waiting to be
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117 static xQueueHandle xRxedChars;
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118 static xQueueHandle xCharsForTx;
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120 /*-----------------------------------------------------------*/
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122 /* Communication flag between the interrupt service routine and serial API. */
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123 static volatile portLONG *plTHREEmpty;
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126 * The queues are created in serialISR.c as they are used from the ISR.
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127 * Obtain references to the queues and THRE Empty flag.
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129 extern void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, portLONG volatile **pplTHREEmptyFlag );
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131 /*-----------------------------------------------------------*/
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133 xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
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135 unsigned portLONG ulDivisor, ulWantedClock;
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136 xComPortHandle xReturn = serHANDLE;
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137 extern void ( vUART_ISR_Wrapper )( void );
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139 /* The queues are used in the serial ISR routine, so are created from
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140 serialISR.c (which is always compiled to ARM mode. */
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141 vSerialISRCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx, &plTHREEmpty );
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144 ( xRxedChars != serINVALID_QUEUE ) &&
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145 ( xCharsForTx != serINVALID_QUEUE ) &&
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146 ( ulWantedBaud != ( unsigned portLONG ) 0 )
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149 portENTER_CRITICAL();
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151 /* Setup the baud rate: Calculate the divisor value. */
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152 ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;
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153 ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;
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155 /* Set the DLAB bit so we can access the divisor. */
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156 UART0_LCR |= serDLAB;
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158 /* Setup the divisor. */
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159 UART0_DLL = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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161 UART0_DLM = ( unsigned portCHAR ) ( ulDivisor & ( unsigned portLONG ) 0xff );
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163 /* Turn on the FIFO's and clear the buffers. */
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164 UART0_FCR = ( serFIFO_ON | serCLEAR_FIFO );
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166 /* Setup transmission format. */
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167 UART0_LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;
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169 /* Setup the VIC for the UART. */
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170 VICIntSelect &= ~( serUART0_VIC_CHANNEL_BIT );
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171 VICIntEnable |= serUART0_VIC_CHANNEL_BIT;
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172 VICVectAddr1 = ( portLONG ) vUART_ISR_Wrapper;
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173 VICVectCntl1 = serUART0_VIC_CHANNEL | serUART0_VIC_ENABLE;
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175 /* Enable UART0 interrupts. */
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176 UART0_IER |= serENABLE_INTERRUPTS;
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178 portEXIT_CRITICAL();
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182 xReturn = ( xComPortHandle ) 0;
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187 /*-----------------------------------------------------------*/
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189 signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
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191 /* The port handle is not required as this driver only supports UART0. */
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194 /* Get the next character from the buffer. Return false if no characters
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195 are available, or arrive before xBlockTime expires. */
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196 if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
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205 /*-----------------------------------------------------------*/
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207 void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
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209 signed portCHAR *pxNext;
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211 /* NOTE: This implementation does not handle the queue being full as no
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212 block time is used! */
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214 /* The port handle is not required as this driver only supports UART0. */
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216 ( void ) usStringLength;
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218 /* Send each character in the string, one at a time. */
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219 pxNext = ( signed portCHAR * ) pcString;
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222 xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
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226 /*-----------------------------------------------------------*/
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228 signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
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230 signed portBASE_TYPE xReturn;
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232 /* This demo driver only supports one port so the parameter is not used. */
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235 portENTER_CRITICAL();
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237 /* Is there space to write directly to the UART? */
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238 if( *plTHREEmpty == ( portLONG ) pdTRUE )
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240 /* We wrote the character directly to the UART, so was
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242 *plTHREEmpty = pdFALSE;
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243 UART0_THR = cOutChar;
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248 /* We cannot write directly to the UART, so queue the character.
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249 Block for a maximum of xBlockTime if there is no space in the
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251 xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );
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253 /* Depending on queue sizing and task prioritisation: While we
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254 were blocked waiting to post interrupts were not disabled. It is
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255 possible that the serial ISR has emptied the Tx queue, in which
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256 case we need to start the Tx off again. */
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257 if( ( *plTHREEmpty == ( portLONG ) pdTRUE ) && ( xReturn == pdPASS ) )
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259 xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );
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260 *plTHREEmpty = pdFALSE;
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261 UART0_THR = cOutChar;
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265 portEXIT_CRITICAL();
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269 /*-----------------------------------------------------------*/
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271 void vSerialClose( xComPortHandle xPort )
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273 /* Not supported as not required by the demo application. */
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276 /*-----------------------------------------------------------*/
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